The present invention relates to installation tools for setting pull type fasteners of a type which include a pin and collar and/or sleeve installed by the application of a relative axial force applied between the pin and collar and/or sleeve. In such fasteners the pin member typically has a pin portion with a plurality of pull grooves for being gripped by the installation tool whereby the relative axial force can be applied. Frequently the pin portion is severable and removed after installation and is referred to as a pintail or pintail portion. More particularly the installation tool includes a nose assembly having a jaw assembly or structure with a plurality of gripping jaws with teeth for gripping the pull grooves to apply such axial force.
Numerous types of multi-pieced fasteners are installed by the application of a relative axial force. Such fasteners can include a pin and sleeve and/or collar, and be of types such as those shown in the U.S. Pat. No. 2,531,048 issued Nov. 21, 1950, U.S. Pat. No. 4,432,679 issued Feb. 21, 1984 and U.S. Pat. No. 4,472,096 issued Sep. 18, 1984. Such fasteners have a pin with a pintail portion with pull grooves and have been installed by a pull tool having a nose assembly with a plurality of movable chuck jaws. Examples of such nose assemblies are noted in the '048 patent (supra) and the details of such are exemplified in the U.S. Pat. No. 3,107,806 issued Oct. 22, 1963. The chuck jaws have teeth adapted to mate with and grip the pull grooves on the fastener pin.
With such jaw assemblies it is possible under certain conditions, such as initial pin insertion between the jaws, for the jaws to move out of axial alignment with each other. When such misalignment occurs and the tool is actuated, the pull grooves on the pin can be gripped by less than the full complement or engagement of teeth on one or more of the jaws which can lead to malfunctions such as stripping of the pull grooves, jamming of the pintail, excessive wear or stripping of the jaw teeth, and/or ultimate failure of one or more jaws.
One solution to such problems was to provide a structure in which the jaws, conventionally constructed of hardened steel, are secured to an elastomeric support or jaw follower structure such that the jaws are generally axially fixed relative to each other whereby relative movement and axial misalignment is substantially precluded. This is shown in the U.S. Pat. No. 4,347,728 issued on Sep. 7, 1982. However, here the jaws are radially fixed at one end and thus could still be articulated radially somewhat non-uniformly and out of phase and circumferentially relative to each other. That structure did provide an improvement; however, when one of the jaws eventually failed or became detached from the elastomeric support structure, the entire jaw assembly had to be replaced. Subsequently an improvement was made on that type of structure in U.S. Pat. No. 4,598,572 which provided the advantages of the prior structure of the '728 patent, supra, but had the jaws removably secured to an elastomeric structure which permitted replacement and facilitated assembly of individual jaw members. Even here, however, some of the typical gripper jaw nose assembly problems remained since the jaws could articulate separately and the pull portion or pintail of the pin could still be moved off-center upon initial insertion between the jaws creating uneven gaps between jaws. Thus with this type of support structure the jaws could still get out of phase with each other and become unevenly supported when engaged with the pull grooves on the pin.
The present invention provides an improvement in both the support and alignment of the jaws. As such the present design maintains the jaws axially, radially and circumferentially synchronized or in phase, inhibiting out of phase conditions which could result in misalignment of jaw teeth. An additional benefit is that there essentially are no open gaps between jaws prior to pin insertion and hence, no opportunity for the pull portion or pintail upon initial insertion to create uneven gaps between jaws which could result in misalignment.
Thus in the present invention the jaw assembly or structure includes a configuration somewhat like that of the well known drill chucks sometimes referred to as JACOBS.RTM. chucks. As such in the present invention, the jaws are configured to be mounted matingly in radially angled or inclined cylindrical tracks or guide slots. However, similar track or hole guided jaw structures are not new and have been used in fastener installation tools. See U.S. Pat. No. 2,053,718 and U.S. Pat. No. 2,053,719 both issued Sep. 8, 1936. In the present invention, however, unique means are provided by which the jaws are axially supported and guided and circumferentially restricted to be synchronized or in phase with each other. In addition a jaw follower with a jaw retainer in the form of an elastomeric support structure is used that also serves as a shock attenuation member. Thus in the present invention, the combination of the use of guide tracks which are shaped to restrict and control relative circumferential and radial movement between the jaws and a jaw follower with an elastomeric jaw retainer which maintains axial alignment while permitting desired articulation results in an improved jaw structure.
It is common for a manufacturing facility to assemble workpieces utilizing fasteners of essentially the same type but of different diameters. Such fasteners can be installed with a single installation tool. However, the nose assembly may have to be changed to provide jaws compatible with the different diameters especially where a pintail portion with pull grooves is being gripped. In this regard it is not uncommon for pins of different diameters to have pull grooves of different pitches. In the present invention, an alternate jaw structure is shown in which a single nose assembly can be utilized to install similar fasteners of two different diameters with pull grooves of different pitches.
Some pull type fasteners are of the type in which the pin portion to be gripped is smooth such as shown in U.S. Pat. No. 4,708,553, issued Nov. 24, 1987. The present invention can be effectively utilized with such fasteners and in such cases the jaw teeth can be provided to be somewhat sharper to facilitate biting into the smooth pin portion to enhance gripping. Here the jaws again are maintained in phase resulting in uniform biting action and gripping of the smooth pin portion.
Thus it is an object of the present invention to provide a jaw assembly or structure for pull tools for setting pull type fasteners of the type having a pin with pull grooves to be gripped by jaws of the jaw assembly and in which the jaws are maintained in phase with each other by maintaining axial and circumferential alignment between the jaws whereby uniform gripping of the pull grooves is provided.
It is an object of the present invention to provide a jaw assembly for pull tools for setting pull type fasteners of the type having a pin with a pull portion to be gripped by jaws of the jaw assembly and in which the jaws are maintained in phase with each other by maintaining axial and circumferential alignment between the jaws whereby uniform gripping of the pull portion is provided.
It is still another object of the present invention to provide a jaw assembly for a pull tool which jaw assembly can be used to install similar fasteners having pull portions with pull grooves of at least two different diameters and/or pull groove pitches.
It is another general object to provide a new and improved jaw assembly for pull tools for setting pull type fasteners of the type having a pin with pull grooves.
It is also a general object to provide a new and improved jaw assembly for pull tools for setting pull type fasteners of the type having a pin with a pull portion which is generally smooth.
It is another object to provide a new and improved nose assembly for pull tools having a jaw structure of a type as noted above and in which the jaws are held open in their deactuated condition to facilitate insertion of a pull portion in clearance and for gripping the pull portion upon actuation to the closed position by the pull tool and release of the pull portion upon the jaws being returned to an open, clearance position with the pull tool being returned to its deactuated condition.
Other objects, features, and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, in which: